1. Not to defend any of these restaurants, as I have only been to one, but I question whether it is possible to satisfy any group of 8th grade students, especially if you are trying to provide 'healthy' choices, on a reasonable budget.
2. Two of these restaurants (Christiana Campbell's and Michie) were almost certainly chosen because of their educational/entertainment benefits, rather than specifically because their food quality. Your students may not have valued that very highly (or the e/e benefits may not have actually been very good either).